Two possible circumbinary planets in the eclipsing post-common envelope system NSVS 14256825

TL;DR

This study analyzes eclipse timing variations in the NSVS 14256825 binary system, suggesting the possible presence of two circumbinary planets based on orbital period changes, though alternative explanations remain possible.

Contribution

First to propose the existence of two circumbinary planets around NSVS 14256825 using eclipse timing variations analysis.

Findings

Orbital periods of potential planets are approximately 3.5 and 6.9 years.

Estimated planetary masses are about 2.9 and 8.1 Jupiter masses.

Orbital variations could be explained by light travel time effects due to these planets.

Abstract

We present an analysis of eclipse timings of the post-common envelope binary NSVS 14256825, which is composed of an sdOB star and a dM star in a close orbit (P_{orb} = 0.110374 days). High-speed photometry of this system was performed between July, 2010 and August, 2012. Ten new mid-eclipse times were analyzed together with all available eclipse times in the literature. We revisited the (O-C) diagram using a linear ephemeris and verified a clear orbital period variation. On the assumption that these orbital period variations are caused by light travel time effects, the (O-C) diagram can be explained by the presence of two circumbinary bodies, even though this explanation requires a longer baseline of observations to be fully tested. The orbital periods of the best solution would be P_c ~ 3.5 years and P_d ~ 6.9 years. The corresponding projected semi-major axes would be a_c i_c ~ 1.9 AU and a_d i_d ~ 2.9 AU. The masses of the external bodies would be M_c ~ 2.9 M_{Jupiter} and M_d ~ 8.1 M_{Jupiter}, if we assume their orbits are coplanar with the close binary. Therefore NSVS 14256825 might be composed of a close binary with two circumbinary planets, though the orbital period variations is still open to other interpretations.